With the development of science and technology, fuel vehicles are being replaced by environment friendly and energy saving electric vehicles. However, the popularization of the electric vehicles encounters some problems, among which high driving mileage and fast charging technology have become a major problem in the promotion of electric vehicles.
Currently, large-capacity batteries are used in most electric vehicles. However, although these batteries may enhance the endurance time of the electric vehicle, they make a charging time too long. Although a specialized DC (direct current) charging station may charge a battery quickly, problems such as high cost and large occupied area make the popularity of such an infrastructure encounter a certain difficulty. Moreover, because of a limited space of the vehicle, an in-vehicle charger may not satisfy the requirement of a charging power due to the limitation of its volume.
A charging solution currently used in the market comprises the following solutions.
Solution (1)
As shown in FIGS. 1-2, an in-vehicle charge-discharge device in this solution mainly includes a three-phase power transformer 1′, a three-phase bridge circuit 2′ consisting of six thyristor elements, a constant-voltage control device AUR, and a constant-current control device ACR. However, this solution causes a serious waste of space and cost.
Solution (2)
As shown in FIG. 3, an in-vehicle charge-discharge device in this solution includes two charging sockets 15′, 16′ to adapt to the single-phase/three-phase charging, which increases the cost. A motor driving loop includes a filtering module consisting of an inductor L1′ and a capacitor C1′. When a motor is driven, a loss of a three-phase current is generated when it flows through the filtering module, which causes a waste of an electric quantity of a battery. With this solution, during the charging or discharging operation, an inverter 13′ rectifies/inverts an AC (alternating current) electricity, and the voltage after the rectifying/inverting may not be adjusted, such that a battery operation voltage range is narrow.
Therefore, most AC charging technologies currently used in the market are a single-phase charging technology, which has disadvantages of low charging power, long charging time, large hardware volume, single function, restriction by voltage levels of different regional grids, etc.
In addition, when the electric vehicle is charged or discharged by means of the AC charging technologies, neither the charging pile and the load can obtain information about the electric vehicle, nor the vehicle can obtain information about the peripheral apparatus. Moreover, the bus data communication technology requires a dedicated data harness, thus increasing manufacturing cost and maintenance difficulty and causing unstable factors to the data transmission in the electric vehicle. In addition, due to a limitation of the national standard charging gun, each of seven wires in the charging gun has its own functions, and thus no spare wire can be used to erect the dedicated communication bus.
There are currently a variety of vehicle bus standards, in which the CAN bus is widely used. These buses require dedicated data harnesses, and due to the limitation of the charging gun standard, a number of the dedicated data harnesses cannot be increased. Therefore, the existing bus technologies do not have spare harness and do not have simplicity and applicability.